The present invention relates to a method of controlling a plurality of arrangements which are actuatable with a hydraulic working medium substantially one after the other, in underground mining works.
The arrangements which are to be controlled are, for example, return cylinder-piston units and cylinder-piston units of underground supports connected with return cylinders during movement process. Particularly, the supports in this case are mine roof supports. Moreover, these arrangements can be formed by respective hydraulically actuatable cylinder-piston units which are used in supporting process for level control of an excavation machine.
The specific features of such hydraulically actuatable arrangements is that mainly they are not actuated simultaneously and electrically controlled for this purpose, but instead they are supplied with hydraulic working medium substantially one after the other at certain time points.
Consumers of electric energy are associated with these cylinder-piston units, for example in form of electromagnetic valves, which together with respective control devices are connected with an electric power supply in intrinsically safe designs. The control devices with integrated input and output blocks as well as computer units perform, for example, exact subsequent movement of the cylinder-piston units of the displaceable cap elements in dependence upon the positions of the return cylinder-piston units or the level control of an excavation device in accordance with the respective local conditions.
Electrical intrinsically safe power supplies have, however, only a limited electrical power. Therefore, only so many control devices and current-supplying consumers are associated with one power supply, which can be supplied with power in current-supplying condition from the respective power supply. This approach however possesses the disadvantage that a greater number of electro-hydraulic control circuits is necessary, with the respective required electrical and mechanical expenditures. This is especially disadvantageous in conditions of underground mining works.